In the dream time hours of the night one of the exchange data-stores went offline. The steps to resolve the issue were put in place and handled swiftly by the administrator on duty; but what was the cause.

After some digging I arrive at the reason why the data-store went offline. Found in the Windows Application event ID 9630 the database had reached the logical side equal to the physical size of the data base and that being 250GB. Thus the database size had exceed the size limit of 250GB

Exchange then dismounted the database preventing further access. My take on this is that Microsoft expects users with large dB’s to have multiple storage servers. Well I am balling with a budget here so that is not happening anytime soon.

So how does one get around this?

Well simple; You follow the steps here on Microsoft Technet. And the procedure in below:

You can get the GUID of a database by running the following command in the Exchange Management Shell: Get-MailboxDatabase -Identity "<server name><storage group name><database name>" | Format-Table Name, GUID

If the Database Size Limit in GB DWORD exists for the subkey, change its value to the desired size in gigabytes.

If the Database Size Limit in GB DWORD does not exist for the subkey, create a new DWORD with that name, and then set its value to the desired size in gigabytes.